Merge pull request #305 from undingen/dup_guards

Don't emit duplicate attr guards

src/asm_writing/rewriter.cpp

@@ -174,6 +174,8 @@ void Rewriter::_addGuardNotEq(RewriterVar* var, uint64_t val) {
 }
 
 void RewriterVar::addAttrGuard(int offset, uint64_t val, bool negate) {
+    if (!attr_guards.insert(std::make_tuple(offset, val, negate)).second)
+        return; // duplicate guard detected
     rewriter->addAction([=]() { rewriter->_addAttrGuard(this, offset, val, negate); }, { this }, ActionType::GUARD);
 }
 

src/asm_writing/rewriter.h

@@ -17,6 +17,9 @@
 
 #include <map>
 #include <memory>
+#include <tuple>
+
+#include "llvm/ADT/SmallSet.h"
 
 #include "asm_writing/assembler.h"
 #include "asm_writing/icinfo.h"
@@ -248,6 +251,8 @@ private:
     bool is_arg;
     Location arg_loc;
 
+    llvm::SmallSet<std::tuple<int, uint64_t, bool>, 4> attr_guards; // used to detect duplicate guards
+
     // Gets a copy of this variable in a register, spilling/reloading if necessary.
     // TODO have to be careful with the result since the interface doesn't guarantee
     // that the register will still contain your value when you go to use it